Re: adaptive cursor sharing and bind peeking

From: Mohamed Houri <mohamed.houri_at_gmail.com>
Date: Thu, 30 May 2013 14:12:53 +0200
Message-ID: <CAJu8R6hr3Xx9490q_bsqAzvMeSzsytwYZdxvBpO-ekMUV-gveA_at_mail.gmail.com>



According to the tests I have done, I am inclined to say that Carlos description is correct. If I have already a child cursor that is bind sensitive, bind aware and shareable for a bind variable that favors (for example an index range scan) and then I execute the same query with a different bind variable which is also favoring the same index range scan, It will share the same child cursor. I have to test that again but I am quite confident that it will work as described. However, I have found situations where this smooth ACS working is disturbed

http://hourim.wordpress.com/2013/04/04/what-can-impeach-adaptive-cursor-sharing-kicking-off/

Best regards

Mohamed Houri

2013/5/30 Jonathan Lewis <jonathan_at_jlcomp.demon.co.uk>

>
> Carlos,
>
> This doesn't seem to agree with a blog post that Randolf Geist wrote some
> time ago:
> http://oracle-randolf.blogspot.co.uk/2011/01/adaptive-cursor-sharing.html
>
> He does mention a bug, relating to ACS not working properly with PL/SQL,
> and presumably that's fixed by now; even so, "checking before every
> EXECUTION" doesn't seem to match his observations.
>
> Regards
> Jonathan Lewis
>
>
> ________________________________________
> From: oracle-l-bounce_at_freelists.org [oracle-l-bounce_at_freelists.org] on
> behalf of Carlos Sierra [carlos.sierra.usa_at_gmail.com]
> Sent: 30 May 2013 11:35
> To: ax.mount_at_gmail.com
> Cc: Christian Antognini; oracle-l_at_freelists.org
> Subject: Re: adaptive cursor sharing and bind peeking
>
> Once it is bind aware on every execution it looks at the values of binds
> ...--
> http://www.freelists.org/webpage/oracle-l
>
>
>

-- 
Bien Respectueusement
Mohamed Houri


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Received on Thu May 30 2013 - 14:12:53 CEST

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